The main object of this project is to determine the nature of the regulatory mechanisms controlling protein synthesis during normal development of the mouse central nervous system. The appearance of multiple species of the tissue specific S-100 protein during postnatal development of the mouse central nervous system will be monitored. At times, when specific S-100's appear it will be determined if this is the result of de novo protein synthesis or more simply a case of protein interconversion. Experiments are also to be performed in which mouse mutants showing abnormal development of the central nervous system will be surveyed for defective rates of protein synthesis.